Resin sealing method for electronic part and mold used for the method

ABSTRACT

An upper mold, a lower mold, a middle mold, and a release film are used in a method of resin sealing of an electronic component. The release film is sandwiched between the lower mold and the middle mold and held under a prescribed tension to cover a cavity of the lower mold. A cavity side surface is also covered with the release film. Therefore, releasability of a cured resin from the cavity side surface is increased. As a result, the cured resin is prevented from being damaged near the cavity side surface.

TECHNICAL FIELD

The present invention relates to a method of resin sealing of asubstrate having an electronic component mounted thereon, and to a moldused in the method.

BACKGROUND ART

A mold having a two-mold structure consisting of an upper mold and alower mold as disclosed in a patent document 1 described below, forexample, has been conventionally used as a mold for transferlessmolding. In a method of resin sealing of an electronic component usingthe mold of the two-mold structure, a problem must be avoided which iscaused by failure of separation of a molded resin from the mold at moldopening. Therefore, a resin is molded with a release film interposedbetween a melting resin and the mold. In this situation, the releasefilm is attracted through a plurality of holes provided in the mold.With this suction, the release film adheres to a surface of the mold.Therefore, the release film is prevented from moving apart from thesurface of the mold and contacting the electronic component. As aresult, damaging of the electronic component is prevented.

On the other hand, another method of resin sealing of an electroniccomponent has also been conventionally used, in which method a mold isset to a vacuum state to introduce a resin into a space inside the mold.In this method, the mold is in a clamped state and air inside the moldis evacuated by a suction device. Molding of the resin is performed wellwith this method because the resin is introduced evenly inside the mold.Therefore, it is desirable to use both of the method using the releasefilm and the method of molding the resin with the mold set to the vacuumstate.

When the mold is set to the vacuum state, however, a force of attractiondrawing the release film to inside of the mold sometimes becomes largerthan a force of attraction of the suction device drawing the releasefilm toward the surface of the mold. A problem of the release filmcontacting the electronic component inside the mold occurs in thissituation. Therefore, when the mold of the two-mold structure is used,it is difficult to use both of the method of resin sealing using therelease film and the method of resin sealing in which the resin isintroduced into the mold by setting the mold to the vacuum state.

Patent Document 1: Japanese Patent Laying-Open No. 2002-043345 (See Page15 and FIG. 13)

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

The inventor of the present application has invented a mold having athree-mold structure for using both of a method of using a release filmand a method of setting a mold in a vacuum state.

The mold of the three-mold structure has a middle mold besides an uppermold and a lower mold. The middle mold is inserted between the uppermold and the lower mold and is used to press the release film againstthe lower mold during resin molding. Therefore, the release film isprevented from moving apart from the lower mold and contacting anelectronic component even when a resin is molded with the mold in avacuum state.

Releasability of the resin from an internal side surface of a cavity islow, however, since the internal side surface of the cavity directlycontacts the resin without interposition of the release film. Therefore,a cured resin is cracked near the internal side surface of the cavity atmold opening because the cured resin is not separated from an internalside surface of the middle mold.

The present invention is made in view of the above-described problem. Anobject of the present invention is to prevent cracking of a cured resinnear an internal side surface of a cavity at mold opening in a method ofresin sealing of an electronic component, in which method a resin ismolded while a release film is pressed by a middle mold of a mold of athree-mold structure against a surface of a lower mold and while themold is set to a vacuum state.

Means for Solving the Problems

A method of resin sealing of an electronic component according to thepresent invention is a method of resin sealing of an electroniccomponent in a cavity using an upper mold, a lower mold opposite to theupper mold, a middle mold provided between the upper mold and the lowermold, and a release film covering the cavity of the lower mold.

In the method, first an unsealed substrate having the electroniccomponent mounted thereon is attached to the upper mold. Then, a wholesurface of the cavity is covered with the release film while the releasefilm is sandwiched between the lower and middle molds. Thereafter, theupper mold and the lower and middle molds are clamped to immerse theelectronic component in a melting resin in the cavity. The melting resinis then cured to form a cured resin. Then, the upper, lower and middlemolds are opened. A sealed substrate having the electronic componentenveloped in the cured resin is removed from the upper mold.

According to this method, the resin is molded with the cavity having notonly a bottom surface but also a side surface covered with the releasefilm. With this, releasability of the cured resin from the side surfaceof the cavity is increased. Therefore, the cured resin is prevented frombeing damaged near the side surface of the cavity when the sealedsubstrate is removed from the cavity. A mold according to the presentinvention is used in the method of resin sealing of an electroniccomponent described above.

The foregoing and other objects, features, aspects and advantages of thepresent invention will become more apparent from the following detaileddescription of the present invention when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a substrate having a semiconductor chip for resin sealingmounted thereon according to a first embodiment. The substrate beforeresin sealing is shown on a left side and the substrate after resinsealing is shown on a right side.

FIG. 2 is a plan view of a layout of a resin sealing apparatus.

FIG. 3 is a cross-sectional view of a mold according to the embodiment,in which upper, lower and middle molds are opened.

FIG. 4 is an enlarged cross-sectional view of a main portion of the moldshown in FIG. 3, in which a release film is sandwiched between the lowerand middle molds.

FIG. 5 is an enlarged cross-sectional view of the main portion of themold shown in FIG. 3, in which the substrate shown in FIG. 1 and a resinmaterial are supplied into the mold.

FIG. 6 is an enlarged cross-sectional view of the main portion of themold shown in FIG. 3, in which the substrate shown in FIG. 1 is mountedon the upper mold and the resin material melts in a cavity withapplication of heat.

FIG. 7 shows the upper mold of the mold shown in FIG. 6 seen from adownside, in which the substrate shown in FIG. 1 is mounted on an uppermold surface.

FIG. 8 shows another example of the upper mold of the mold shown in FIG.6 seen from a downside, in which the substrate shown in FIG. 1 ismounted on an upper mold surface.

FIG. 9 is an enlarged cross-sectional view of the main portion of themold shown in FIG. 3, in which air inside the mold is evacuated and themold is set to a vacuum state.

FIG. 10 is an enlarged cross-sectional view of the main portion of themold shown in FIG. 3, in which the substrate shown in FIG. 1 is to beimmersed in a melting resin.

FIG. 11 is an enlarged cross-sectional view of the main portion of themold shown in FIG. 3, in which the mold is completely clamped and thesubstrate shown in FIG. 1 is entirely immersed in the melting resin.

FIG. 12 is an enlarged cross-sectional view of the main portion of themold shown in FIG. 3, in which the substrate after resin sealing hasjust been released from the lower mold.

FIG. 13 is an enlarged cross-sectional view of the main portion of themold shown in FIG. 3, in which the substrate shown in FIG. 1 has justbeen removed from the upper mold.

FIG. 14 shows a substrate having a semiconductor chip for resin sealingmounted thereon according to a second embodiment. The substrate beforeresin sealing is shown on a left side and the substrate after resinsealing is shown on a right side.

FIG. 15 is an enlarged cross-sectional view of a mold according to thesecond embodiment, in which the substrate shown in FIG. 14 is mounted onan upper mold surface.

FIG. 16 is an enlarged cross-sectional view of a main portion of themold according to the second embodiment, in which the mold is completelyclamped and the substrate shown in FIG. 14 is entirely immersed in amelting resin.

FIG. 17 shows a substrate having a semiconductor chip for resin sealingmounted thereon according to a third embodiment. The substrate beforeresin sealing is shown on a left side and the substrate after resinsealing is shown on a right side.

FIG. 18 is an enlarged cross-sectional view of a mold according to thethird embodiment, in which the substrate shown in FIG. 17 is mounted onan upper mold surface.

FIG. 19 is an enlarged cross-sectional view of a main portion of themold according to the third embodiment, in which the mold is completelyclamped and the substrate shown in FIG. 17 is entirely immersed in amelting resin.

DESCRIPTION OF THE REFERENCE SIGNS

1: substrate, 2: semiconductor chip, 4: unsealed substrate, 5: resinmaterial, 6: melting resin, 7, 59: sealing and molding portion, 10, 62:cured resin, 11: sealed substrate, 13: upper mold, 14: lower mold, 15:middle mold, 16: cavity, 17, 57: release film.

BEST MODES FOR CARRYING OUT THE INVENTION First Embodiment

A method of resin sealing according to a first embodiment and a moldused in the method will now be described referring to FIGS. 1-11.

A substrate 1 to be resin-sealed using the method of resin sealingaccording to this embodiment is described using FIG. 1. Substrate 1 hasa circular or polygonal shape. A plurality of semiconductor chips 2(hereafter referred to as “chip 2”) are mounted on one surface ofsubstrate 1. Substrate 1 and chip 2 are electrically connected to eachother with a wire 3.

One side of a sealed substrate 11 has a sealing and molding portion 7 onwhich a resin enveloping chip 2 is molded and a substrate rim portion 8which is a portion around sealing and molding portion 7 on which theresin is not molded. The other surface of substrate 1 on a backside ofsealing and molding portion 7 is a non-mounting surface 9 on which chip2 is not mounted. A cured resin 10 is formed on sealing and moldingportion 7 after the resin sealing. Examples of substrate 1 include a BGA(Ball Grid Array) substrate and a CSP (Chip Size Package) substrate.

A resin sealing apparatus of this embodiment is described using FIG. 2.A resin sealing apparatus 70 of this embodiment has a mold 12. Mold 12is a mold for transferless molding having a three-mold structure. Thethree-mold structure consists of an upper mold 13, a lower mold 14 and amiddle mold 15. Mold 12 is mounted on a press unit 71.

Resin sealing apparatus 70 includes a loader unit 73 having a functionof supplying an unsealed substrate 4 and a resin material 5 into mold 12and a function of removing sealed substrate 11 from mold 12. Unsealedsubstrate 4 is stored in an in-magazine unit 74 before it is transportedto loader unit 73. Resin material 5 is stored in a resin material unit75 before it is transported to loader unit 73. Sealed substrate 11 isremoved from press unit 71 by loader unit 73 and stored in anout-magazine unit 76.

In addition, each of in-magazine unit 74 and out-magazine unit 76 isprovided with a magazine cassette of a slit type on which a plurality ofsubstrates 1 (unsealed substrate 4 or sealed substrate 11) are mountedspaced apart from each other. In a process of resin sealing of the firstembodiment, substrate 1 is stored in the magazine cassette with itssealing and molding portion 7 facing downward.

Press unit 71 clamps and opens mold 12. Lower mold 14 is moved upwardand downward by press means such as a mechanism utilizing a pressure ofa working fluid or an electric press mechanism. Middle mold 15 is movedupward and downward by press means other than the press means of lowermold 14.

In addition, a feed portion 22 for feeding a release film 17 and atake-up portion 23 for taking up release film 17 are provided near mold12. Release film 17 moves from feed portion 22 to take-up portion 23 ina direction of an arrow shown in FIG. 2. Feed portion 22 and take-upportion 23 can also increase or decrease a tension of release film 17.

Loader unit 73 includes transfer means 78 such as a mechanical chucktransfer mechanism or a robot arm transfer mechanism. Therefore,unsealed substrate 4 and resin material 5 are transferred by transfermeans 78 and move inside mold 12 in a substantially horizontaldirection. An upper portion of transfer means 78 is used for supplyingunsealed substrate 4 and removing sealed substrate 11, and a lowerportion of transfer means 78 is used for supplying resin material 5.

Resin material unit 75 includes a storage portion (not shown) such as aresin storage locker for storing a granular resin material 5 for use. Acontrol unit 77 for controlling each of aforementioned units 71-76 and avacuum unit is also provided.

An outline of the method of resin sealing of an electronic component ofthis embodiment will now be described.

First, unsealed substrate 4 is transported from in-magazine unit 74 toan upper portion of loader unit 73. Then, resin material 5 istransported from resin material unit 75 to a lower portion of loaderunit 73. Thereafter, unsealed substrate 4 and resin material 5 aretransported from loader unit 73 to press unit 71. Then, resin sealing ofunsealed substrate 4 is performed in mold 12 and thereby sealedsubstrate 11 is obtained.

Then, sealed substrate 11 is removed from mold 12 and mounted on theupper portion of loader unit 73. Thereafter, sealed substrate 11 istransported from loader unit 73 to out-magazine unit 76.

The mold of this embodiment is described using FIG. 3.

As shown in FIG. 3, mold 12 of this embodiment includes upper mold 13,lower mold 14 and middle mold 15. Upper mold 13 does not move.Therefore, a position of an upper mold surface 18 of upper mold 13 isfixed. Lower mold 14 moves upward and downward. Lower mold 14 includes alower mold surface 19 and a convex portion 27 projected from lower moldsurface 19. Convex portion 27 has a cavity surface 26. Middle mold 15 islocated between upper mold 13 and lower mold 14, and is moved upward anddownward. Middle mold 15 includes an upper mold-side mold surface 24 anda lower mold-side mold surface 25. As shown in FIG. 3, middle mold 15also includes a housing portion 43 for housing a chuck member 37 holdingsubstrate 1 and a through hole 44 into which lower mold 14 is inserted.

Upper mold 13 also includes a substrate mechanism 29, a seal member 30and a suction and exhaust hole 31. Substrate mechanism 29 fixes unsealedsubstrate 4 on upper mold surface 18 with chip 2 facing downward. Sealmember 30 fills a clearance between upper mold 13 and middle mold 15when upper mold 13, lower mold 14 and middle mold 15 are clamped.Suction and exhaust hole 31 communicates with a vacuum mechanism forsetting a space inside the mold to a vacuum state when upper mold 13,lower mold 14 and middle mold 15 are clamped.

In addition, as shown in FIG. 3, substrate mechanism 29 in upper mold 13includes a suction portion 32 for adhering to substrate 1 (unsealedsubstrate 4 and sealed substrate 11) by suction and a holder portion 33for holding substrate 1.

Suction portion 32 of upper mold 13 adheres to substrate 1 by suction.Suction portion 32 includes a permeable member 34, a communicationgroove 35 and a suction and exhaust hole 36. Permeable member 34 adheresto non-mounting surface 9 of substrate 1 by suction. Communicationgroove 35 communicates with permeable member 34. Suction and exhausthole 36 communicates with communication groove 35 and is connected tothe vacuum mechanism (not shown). The vacuum mechanism attractsnon-mounting surface 9 of substrate 1 via permeable member 34,communication groove 35 and suction and exhaust hole 36.

Holder portion 33 is provided between suction portion 32 and seal member30. Substrate rim portion 8 of substrate 1 is mounted on holder portion33. Holder portion 33 has chuck member 37 having an openingcorresponding to chip 2, an attached rod 38 attached to chuck member 37,a resilient member 40 into which attached rod 38 is inserted, and adriving member 39 for driving attached rod 38.

On the other hand, a film mechanism 28 is provided in lower mold 14.Film mechanism 28 includes a permeable member 45, a communication groove46 communicating with permeable member 45 and a suction and exhaust hole47 communicating with communication groove 46. Suction and exhaust hole47 communicates with a vacuum unit (not shown) for attracting releasefilm 17. The vacuum unit attracts release film 17 toward cavity surface26 via suction and exhaust hole 47, communication groove 46 andpermeable member 45. With this, release film 17 is tightly adhered tocavity surface 26. Therefore, release film 17 covering a whole surfaceof cavity 16 is prevented from moving inside a cavity space 20.

In addition, film mechanism 28 discharges air from cavity surface 26 viasuction and exhaust hole 47, communication groove 46 and permeablemember 45. With this, sealed substrate 11 is readily removed from cavitysurface 26.

An operation during clamping of mold 12 and a detailed structure of mold12 will now be described using FIGS. 4-11.

At mold clamping, first, middle mold 15 moves downward. With this, lowermold-side mold surface 25 comes into contact with release film 17.Thereafter, middle mold 15 further moves downward. With this, releasefilm 17 is sandwiched between lower mold-side mold surface 25 and anupper surface of a sandwiching member 49, as shown in FIG. 4. Anattached rod 50 for supporting sandwiching member 49 is provided on alower surface of sandwiching member 49. In addition, a resilient member55 for resiliently supporting a cavity member 52 is provided on a lowerside of cavity member 52.

In a state of mold opening as shown in FIG. 3, the upper surface ofsandwiching member 49 is in a higher position than lower mold 14 andresilient member 55 is in an expanding state. When lower mold 14 andmiddle mold 15 are clamped, on the other hand, resilient member 55 isset to a contracting state as shown in FIG. 4 by sandwiching member 49and attached rod 50 moving downward.

Next, as middle mold 15 further moves downward with release film 17sandwiched between middle mold 15 and sandwiching member 49, a portionof release film 17 in a space formed with through hole 44 and an openingportion 48 abuts on cavity member 52.

Since cavity member 52 is provided to surround convex portion 27, it canmove upward and downward between lower mold 14 and middle mold 15.Cavity member 52 has a cross section of an L shape. The L shape isformed with a vertical portion and a horizontal portion.

As shown in FIG. 5, the vertical portion of cavity member 52 has anabutting region 53 abutting on substrate rim portion 8 of substrate 1with release film 17 interposed therebetween, a cavity bottom surface 54a arranged around cavity surface 26 and forming a portion of a bottomsurface of cavity 16, and a cavity side surface 54 b forming a sidesurface of cavity 16.

In addition, the horizontal portion of cavity member 52 has an uppersurface abutting on the lower surface of sandwiching member 49 and alower surface which abuts on lower mold surface 19 when cavity member 52moves downward. Resilient member 55 is connected to the lower surface ofthe horizontal portion of cavity member 52 and inserted into a concaveportion provided in lower mold 14.

Next, as middle mold 15 further moves downward with release film 17sandwiched between middle mold 15 and sandwiching member 49, the lowersurface of sandwiching member 49 abuts on the horizontal portion ofcavity member 52, as shown in FIG. 5. In this situation, the wholesurface of cavity 16 is covered with release film 17. In addition,release film 17 is adhered to cavity surface 26 by suction of filmmechanism 28. With this, cavity space 20 shown in FIG. 5 is formed incavity 16.

In the first embodiment, an integrated transfer means 78 has a crosssection of a horizontally oriented U shape, and only tip portions ofhorizontal portions of the horizontally oriented U shape are shown inFIG. 5. In addition, unsealed substrate 4 is fixed on an upper portionof transfer means 78, and resin material 5 is fixed on a lower portionof transfer means 78.

When cavity space 20 is to be formed, middle mold 15 moves downward withrelease film 17 sandwiched between middle mold 15 and sandwiching member49 until the upper surface of sandwiching member 49 reaches a positionlower than abutting region 53 of cavity member 52.

In addition, when film mechanism 28 forcedly attracts release film 17downward, release film 17 tightly adheres to the whole surface of cavity16, that is, to all of cavity surface 26, cavity bottom surface 54 a andcavity side surface 54 b. Therefore, since cavity side surface 54 b iscovered with release film 17 without being exposed, melting resin 6 doesnot directly contact cavity side surface 54 b when melting resin 6 isintroduced into cavity 16. That is, melting resin 6 does not have aportion contacting lower mold 14. In other words, melting resin 6enveloping chip 2 only contacts release film 17 and unsealed substrate4. Therefore, releasability of cured resin 10 from cavity side surface54 b is increased when sealed substrate 11 is removed from lower mold 14and middle mold 15. As a result, generation of a chip or a crack ofcured resin 10 near cavity side surface 54 b is prevented.

In upper mold 13, on the other hand, chuck member 37 and attached rod 38move upward and downward when substrate 1 is sandwiched between chuckmember 37 and upper mold surface 18. Chuck member 37 and attached rod 38are driven by driving member 39 and resilient member 40.

In an operation of holder portion 33, resilient member 40 wound aroundattached rod 38 is first set to a contracting state. In this situation,as shown in FIG. 5, chuck member 37 is separated from upper mold surface18. In this state, unsealed substrate 4 is supplied between chuck member37 and upper mold surface 18 by transfer means 78. Resin material 5 isalso transferred into mold 12 by transfer means 78 together withunsealed substrate 4.

Thereafter, resin material 5 supplied into cavity space 20 is heated tobecome melting resin 6, as shown in FIG. 6. In this state, release film17 covering cavity surface 26 is more reliably prevented from becomingcrinkled by gravitation of melting resin 6.

As shown in FIG. 7, holder portion 33 holds a whole of substrate rimportion 8 of substrate 1 with chuck member 37. Substrate rim portion 8,however, may be held by a chuck nail 41, as shown in FIG. 8.Alternatively, substrate 1 may be fixed to upper mold 13 by a locatinghole 42 provided in substrate rim portion 8 and a locating pin insertedinto the locating hole.

Next, upper mold-side mold surface 24 abuts on seal member 30, as shownin FIG. 9. Thereafter, the vacuum mechanism evacuates air inside aninternal air isolation space 21 via suction and exhaust hole 31communicating with internal air isolation space 21 while seal member 30is compressed. In this situation, abutting region 53 is inserted intothrough hole 44 and abuts on substrate rim portion 8 with release film17 interposed therebetween, as shown in FIG. 10.

With this, chip 2 is immersed in melting resin 6 in cavity space 20together with wire 3. In this situation, abutting region 53 abuts on awhole of substrate rim portion 8. Therefore, melting resin 6 does notleak onto substrate rim portion 8 in a state shown in FIG. 10. Then, asshown in FIG. 11, resin sealing of chip 2 is completed. After a lapse ofa prescribed time, melting resin 6 of a portion near chip 2 is cured andcured resin 10 is molded.

Then, when lower mold 14 moves downward to remove sealed substrate 11from lower mold 14 and release film 17, a clearance is formed betweenrelease film 17 contacting cured resin 10 and cavity surface 26, asshown in FIG. 12. In this situation, sealed substrate 11 is completelyremoved from release film 17 (cavity surface 26) by attracting releasefilm 17 utilizing a function of film mechanism 28.

Then, though not shown in the drawing, lower mold 14 and middle mold 15move downward while sealed substrate 11 is separated from cavity surface26. In this state, sealed substrate 11 is still mounted on upper moldsurface 18.

Thereafter, upper mold 13 and lower and middle molds 14, 15 are opened.Then, chuck member 37 is separated from upper mold surface 18 to removesealed substrate 11 from upper mold 13. In this state, transfer means 78removes sealed substrate 11 from upper mold 13, as shown in FIG. 13.

Second Embodiment

A method of resin sealing of an electronic component according to asecond embodiment of the present invention and a: mold used in themethod will now be described referring to FIGS. 14-16.

It is to be noted that, portions of the mold for resin sealing in thisembodiment indicated with the same reference characters as those of mold12 for resin sealing in the first embodiment have the same structuresand functions as those indicated with the same reference characters inthe first embodiment, and therefore descriptions thereof will not berepeated. Therefore, in this embodiment, differences from the method ofresin sealing of an electronic component of the first embodiment andfrom the mold used in the method will be mainly described.

As shown in FIG. 14, substrate 1 of the second embodiment has a throughhole 56 formed between a region in which wire 3 is connected tosubstrate 1 and a region in which chip 2 contacts substrate 1. Duringresin sealing, a release film 57 described below is used to prevent themelting resin filling through hole 56 from leaking onto non-mountingsurface 9.

Though not shown in FIG. 2, a film unit 72 in this embodiment has amechanism to transfer release film 57 independently of a transfermechanism of release film 17, as described below.

In the method of resin sealing of an electronic component of thisembodiment, release film 57 is supplied between non-mounting surface 9of substrate 1 and upper mold surface 18 of upper mold 13 to cover uppermold surface 18, as shown in FIGS. 15 and 16. Similarly as release film17, release film 57 moves in a direction perpendicular to a papersurface of each of FIGS. 15 and 16. In addition, a weak adhesion layermay be provided on a surface of release film 57 contacting non-mountingsurface 9 to avoid a clearance formed between non-mounting surface 9 andrelease film 57. In this situation, the weak adhesion layer must notremain on non-mounting surface 9 when sealed substrate 11 is removedfrom upper mold 13. When release film 57 covers non-mounting surface 9,resin sealing may be performed with release film 57 entering throughhole 56.

In this embodiment, substrate 1 is similarly provided between upper mold13 and middle mold 15 with a surface having chip 2 mounted thereonfacing downward, as shown in FIG. 15. Thereafter, release film 57 isadhered to upper mold surface 18 by suction. Then, non-mounting surface9 of substrate 1 is mounted on upper mold surface 18 with release film57 interposed therebetween.

As shown in FIG. 16, melting resin 6 then fills a portion near chip 2 aswell as through hole 56, and melting resin 6 is cured to complete resinsealing. In this situation, melting resin 6 is prevented from leakingonto non-mounting surface 9 by release film 57.

Suction portion 32 is desirably switched from a state of evacuating airto a state of discharging air just before clamping of the three molds.With this, release film 57 is pressed against non-mounting surface 9 ofsubstrate 1 by air discharged from permeable member 34. As a result,adhesion of release film 57 to non-mounting surface 9 of substrate 1 isfurther enhanced, and a possibility of the resin flowing ontonon-mounting surface 9 is decreased more reliably.

With the method of resin sealing of an electronic component of thisembodiment as described above, releasability of sealed substrate 11 fromcavity 16 is also increased and, therefore, generation of a chip or acrack of cured resin 10 is prevented.

Third Embodiment

A method of resin sealing of an electronic component according to athird embodiment of the present invention and a mold used in the methodwill now be described referring to FIGS. 17-19.

It is to be noted that, portions of the mold for resin sealing in thisembodiment indicated with the same reference characters as those of mold12 for resin sealing in each of the first and second embodiments havethe same structures and functions as those indicated with the samereference characters in each of the first and second embodiments, andtherefore descriptions thereof will not be repeated. Therefore, in thisembodiment, differences from the method of resin sealing of anelectronic component of each of the first and second embodiments andfrom the mold used in the method will be mainly described.

As shown in FIG. 17, unsealed substrate 4 used in this embodiment has aplurality of chips 2 provided on one surface thereof and wire 3connected to each chip 2 and protruding from the other surface. Unsealedsubstrate 4 of this embodiment has a through hole 58 formed near aposition in which substrate 1 contacts chip 2.

In addition, sealed substrate 11 has sealing and molding portion 7 onwhich cured resin 10 enveloping chip 2 is formed, a sealing and moldingportion 59 for enveloping wire 3 alone, substrate rim portion 8 on whicha resin is not molded, and non-mounting surface 9 on which chip 2 is notmounted. Furthermore, in the method of resin sealing of this embodiment,a resin flows from sealing and molding portion 7 on one surface tosealing and molding portion 59 on the other surface via through hole 58,as shown in FIG. 19. After resin sealing, sealed substrate 11 isobtained which has cured resin 10 formed on one surface thereof and acured resin 62 formed on the other surface.

Upper mold 13 of the third embodiment further includes an upper moldcavity 60 provided in permeable member 34 for housing wire 3 extendingfrom the other surface of substrate 1. This is a difference of mold 12of this embodiment from mold 12 of each of the first and secondembodiments. As shown in FIG. 18, a cavity formation member 61 having aconcave portion corresponding to a position, a size and a shape of wire3 is inserted in upper mold cavity 60.

Cavity formation member 61, however, may not be provided and a concaveportion for housing wire 3 may be formed in permeable member 34. Inaddition, permeable member 34 may not be provided and upper mold cavity60 may be provided in upper mold surface 18. Furthermore, release film57 described in the second embodiment may be supplied betweennon-mounting surface 9 of substrate 1 and upper mold surface 18 to avoidflowing of melting resin 6 into a portion between upper mold cavity 60and non-mounting surface 9 of substrate 1.

In the method of resin sealing of an electronic component of thisembodiment, a substrate 1 is first supplied between upper mold 13 andmiddle mold 15, as shown in FIG. 18. Then, melting resin 6 is suppliedinto cavity space 20, as shown in FIG. 19. Thereafter, lower mold 14 andmiddle mold 15 move toward upper mold 13 until substrate rim portion 8abuts on abutting region 53 of cavity member 52. With this, meltingresin 6 flows from sealing and molding portion 7 on one surface tosealing and molding portion 59 on the other surface via through hole 58.A projection (not shown) may be provided on a surface of cavityformation member 61 to avoid flowing of melting resin 6 into a portionaround cavity formation member 61 in this situation.

With the method of resin sealing of an electronic component of thisembodiment, releasability of sealed substrate 11 from cavity 16 is alsoincreased and, therefore, generation of a chip or a crack of cured resin10 is prevented.

Though the method of resin sealing of an electronic component of eachembodiment described above is used for resin sealing of chip 2 subjectto wire bonding, the method can also be applied to resin sealing of aflip chip substrate having chip 2 mounted thereon without wire 3, or toresin sealing of a wafer level package. In this situation, a meltingresin may be produced using a tablet-shaped resin material 5.

Although the present invention has been described and illustrated indetail, it is clearly understood that the same is by way of illustrationand example only and is not to be taken by way of limitation, the spiritand scope of the present invention being limited only by the terms ofthe appended claims.

1. A method of resin sealing of an electronic component in a cavityusing an upper mold, a lower mold opposite to said upper mold, a middlemold provided between said upper mold and said lower mold and includinga through hole into which said lower mold can be inserted, and a releasefilm covering the cavity of said lower mold; said method comprising thesteps of: attaching to said upper mold an unsealed substrate having saidelectronic component mounted thereon; inserting said lower mold intosaid through hole of said middle mold, while said release film is heldbetween said lower mold and said middle mold; covering a whole surfaceof said cavity with said release film while said release film issandwiched between said lower mold and said middle mold; clamping saidupper mold together with said lower mold and said middle mold to immersesaid electronic component in a melting resin in said cavity; curing saidmelting resin to form a cured resin; opening said upper mold, said lowermold and said middle mold; and removing a sealed substrate having saidelectronic component enveloped in said cured resin from said upper mold.